mensural notation

noun

1.

a system of musical notation of the 13th to the late 16th centuries, marked by the use of note symbols such as the longa and brevis, the absence of bar lines and ties, and the equivalence in value of one note to either two or three of the next smaller degree.

European system of musical notation used from c. 1260 to 1600. It evolved as a method to notate complex rhythms beyond the possibilities of previous notation (neumes) and reached its classical development after 1450. A major step forward was made by Philippe de Vitry in his highly influential treatise Ars nova ("New Art"), written about 1320.